(1) Field of the Invention
The invention relates to the field of switching data grids (or cells), and in particular monitoring devices for a multichannel numeric switch.
(2) Description of the Related Art
The word “grid” is to be taken in its widest sense here, in that it designates all types of messages formed of a multiplicity of fields sequenced according to predetermined formats. In the same way, the word “data” is to be taken in its widest sense, in that it designates all data contained in a message, including the data relating to the message transmitter (or source), the destination(s) of this message, or even the type of message.
Such switches conventionally comprise physical connection circuits, generally referred to as the “physical layer”, connected to a transmission medium which defines the source (or input) communication ports and/or destination (or output) communication ports, to which articles of IT hardware (or machines) are connected. They also comprise a processing unit, generally referred to as the “logic layer”, and a connecting interface between the processing unit and the connecting circuits, for each of the ports, selectively. The processing unit ensures numeric switching of multifield data grids between the different ports, i.e. between a source port and at least one destination port.
These switches therefore form part of a communication installation in which independent physical links permit separation of the data in a manner known as “segmented” and not “diffused”.
In order to ensure good functioning of such an installation the data received by one (or more) destination machine(s) (which will be likened hereinafter to the destination or output communication port to which it is “attached”) must be substantially identical to those transmitted by the source machine (which will be likened hereinafter to the source or input communication port to which it is “attached”).
Due to the complexity of the various connections, the very nature of the transmission media, and the conditions in which the grid exchanges take place, it frequently happens that certain grids deteriorate during their transfer from the source machine to the destination machine. This is particularly so with “COTS”-type switches, which are very widely used in information technology and telecommunications, due in particular to their low cost and the virtually universal format of the grids.
This disadvantage makes switches of the above-mentioned type difficult to use, indeed even unusable, in certain fields of application where the protection of the data is of great importance. This is the case in avionics where the management and control of flight is concerned.
Moreover, it is important that breakdowns and/or loss of functioning are treated.